Threshold plate and assembly



Feb. 21, 1939. w, 1 HENNESSY 147,700

THRESHOLD PLATE AND ASSIEMBLY Filed April Vll, 1936 lNv 0R WALTER J. NNEssY.

ATTORN EY Patented F eb. 21, 1939 UNITED STATES PATENT oFFlcE to Johns-Manville Corporation,

New York,

N. Y., a corporation of New York Application April 11, 1936, Serial No. 73,85)

s claims. (01.2076) This invention relates to a refrigerator assembly, particularly, to the portion thereof adjacent to the threshold, and to an improved threshold plate.

The invention is particularly useful in connection with the thresholds of railwayrefrigerator cars and will be described, for the purpose of illustration, in connection therewith. It is to be understood, however, that the invention is 10 applicable to other refrigerators.

There has been proposed heretofore the use in refrigerator cars of waterproofing means, such as an asphalt-saturated paper over the oor of the car, to prevent Water, formed by the condensation of moisture or melting of ice within the car, from penetrating the floor of the car and interfering with the effectiveness of the insulation therein. In such cars there has been used a threshold plate of steel, against which the bottom of the car door is wedged, when the door is closed.

This metal plate, being an excellent conductor of heat, is strongly influenced as to temperature on either edge portion by the temperature on 25 the opposite side of the door. Thus, if the inside of the -car is refrigerated, the outside of the plate may become frosted, to the extent that the ice thus formed interferes with the opening of the door. Conversely, when the inside of the car 3o is being warmed, as in very cold Weather, then ice may be formed onthe portion of the threshold plate at the inside of the door, also with resultant interference with the opening of the door.

There is need of a threshold plate that minirnizes or eliminates entirely this tendency to frosting on either edge thereof and that is tough, Water-impermeable, and preferably non-corrodible.

It is an object `of the present invention to4 ,o provide a threshold plate and assembly meeting this need. Another object of the invention is to provide an assembly, including the threshold plate, that prevents access of water to the support for the threshold plate and to the lower 5 parts of the framing of the door. Other features and advantages' will appear from the detailed description that follows.

A preferred embodiment of the invention is illustrated in the attached drawing and will be described, for the purpose of exemplication, in connection therewith.

Fig. 1 is a vertical sectional view of a portion of` the refrigerator assembly including my im- 5 provements.

Fig. 2 is a sectional perspective view, partly diagrammatic, of the assembly.

There are shown, in the refrigerator assembly, a door ll, a threshold l2dening a space With the bottom of the door, and a threshold plate I3 disposed in and closing the said space and in contact with the door, when the door is shut. The plate has improved properties and serves a novel function, as will be described later.

Disposed over the floor of the car andextending a substantial distance upwardly over the side walls of the car and, also, upwardly along the edges of the side framing of the door is a suitable waterproofing means. Thus, there may be provided a conventional saturated felt i4, such, for example, as roofing paper, flashed and adhered at its edge portions to a saturated cloth l5 extending upwardly along the side walls and the side framing of the door, as illustrated at positions i6 and lll, respectively. At position I8, the fabric is lapped by the lower portion of the` threshold plate li.

The members li, llt, and it, at their lapping portions, may be adhered to each other by a suitable cementing agent (not shown). Also, these members, at positions of contact with structural parts of the car, likewise may be aclhered to the said parts.

A convenient cementing agent is one including a large proportion of asphalt or tar, applied as a fluent hardenable composition and then hardened, as by evaporation of volatile solvent.

Preferably, the plate i3 is secured to the threshold l2, that is, to the supporting substructure` for the plate, by screws lli or the like that, at their head portions, do not extend above the plane of the plate, as illustrated.

The plate i3 is tough,4 non-corrodible, waterimpermeable, and enective as thermal insulation, as distinguished, for instance, from the thermal conductancev of the formerly used metal threshold plates.-

Such a plate may include a water-impermeable binder, such as rubber and/or polymerized chloroprene, each, if used, being in hardened condition in the finished article'.- Various hard, tough, resinous binders alsofl may be used, as, for example, a plasticized phenol aldehyde resin. However, rubber is satisfactory as a binder, is relatively inexpensive, and gives to the finished assembly particularly desirable features.

Dispersed in the binder and bonded thereby into a unitary article are ller particles, preferably reenforcing fibres, as, for instance, fibres of chrysotile asbestos, crocidolite, jute, or the like.

The following specific example illustrates the composition of a typical plate and the method of making the plate.

In accordance with usual technique, there is made a plastic mixture of rubber with short asbestos libres, conventional admixtures, and solvent or extender. Thus, there may be made a mixture including the several ingredients in about the following proportions:

Ingredients- Parts by weight Pale crepe rubber 12 Chrysotile asbestos 66 Sulphur 4 Vulcanization accelerator-; 1/2 Litharge 1 Lime 1/2 Carbon black 2 Zinc oxide 8 Barytes 6 High-test gasoline, 16 gallons to 100 pounds of the above ingredients.

This mixture is transferred to a sheeter machine, such as described in U. S. Patent 1,771,749, issued to Eisenhart on July 29, 1930, and, by the method described in the said patent, is formed into a sheet of approximately the thickness desired in the finished article.

During this sheeting operation most of the gasoline is evaporated.

The sheeted material is then cut into strips of approximately the length and width desired. These strips arepressed to exact size and the binder therein hardened. For example, the rubber composition described above may be shaped in a die at 100 pounds pressure tothe square inch and kept therein, for about two hours, at a temperature adapted to vulcanize the composition, say, at a temperature corresponding to 60 pounds gauge steam pressure.

'Ihe shaped and hardened slab may then be #y provided with counteisunk holes for receiving the screws I9, may be bevelled or rounded at one or more edges, or may be otherwise machined or trimmed as desired.

The composition described in the immediately preceding specific example, although of density in excess of 100 pounds to the cubic foot, has a specific thermal conductance, in the engineering system of units, of the order of 1.4 to 1.7 British thermal units, in the range of 200 to 800 F.

mean temperature of the specimen being tested.

The dimensions of the threshold plate will, of course, be selected to fit the space presented below the door of the refrigerator. In a typical instance, the plate had a length equal to the width of the door, a width of nine inches and a. thickness of three-eighths inch.

With the plate of the kind described. there is no absorption of water. There is thus eliminated swelling or warping of the plate. Furthermore, there is no tendency of the plate to splinter or separate when struck by'heavy loads, such as the wheels of a hand loading truck. The lplate is non-corrodible and very tough. Also, the plate is eiective in thermal insulation and minimizes, consequently, the transfer of heat` through the plate, thus overcoming the frosting trouble on the cooler edge of the plate.

It will be understood that the details given t are for the purpose of illustration, not restriction, and that variations within the spirit of the invention are intended to be included in the scope of the appended claims.

What I claim is:

1. A refrigerator assembly comprising a iioor, sidewalls, a door, and a threshold plate disposed below and in contact with the door, the said plate being impermeable to water, eil'ective as thermal insulation, tough and non-oorrodible and including a hardened rubber binder and reenforcing libres dispersed therethroughout.

2. A refrigerator assembly comprising a floor, side walls, a door, a threshold defining a space With the bottom of the door, waterproofing means extending over the said floor, to a substantial distance up the side walls, and onto the threshold, and a threshold plate composed of a hardened plastic composition comprising rubber bonded fibres closing the said space and overlapping the portion of the said means extending onto the threshold, so as to provide a water-tight assembly at the lower part of the door assembly.

3. A refrigerator assembly comprising a floor, side walls, a door, a threshold spaced from the bottom of the door, waterproof means extending over the said floor, to a substantial distance up the side walls, and onto the threshold, and a threshold plate positioned between the bottom of the door and the threshold and overlapping the portion of the said means extending onto the threshold so as to form a water-tight construc tion at the lower part of the door, the said plate being impermeable to water, effective as thermal insulation, tough and non-corrodible, and including a hardened binder and reenforcing fibres dispersed throughout the binder.

4. In a refrigerator having a doorway through which freight trucks and the like are moved and a door therefor, a plate disposed over the threshold of said doorway in position to underlie said door when closed, said plate being impermeable to water, effective as thermal insulation, tough and non-corrodible, and comprising successively accreted layers of reinforcing fibers and subsequently hardened binder.

5. In a refrigerator car having a loading and unloading doorway and a door therefor, a plate disposed over the threshold of said doorway in position to underlie said door when closed, said plate being impermeable to water, effective as thermal insulation, tough and non-corrodible, and comprising reinforcing bers dispersed throughout a. hardened rubber binder.

6. In a refrigerator car having a loading and unloading doorway and a door therefor, a plate disposed over the threshold of said doorway in position to underlie said door when closed, said plate being impermeable to water, effective as thermal insulation, tough and non-corrodible, and comprising successively accreted layers of asbestos reinforcing fibers and subsequently hardened rubber binder.

7. In a refrigerator lincluding a doorway through which freight trucks and the like are moved and a door therefor, a threshold plate for said doorway in position to underlie said door when closed, said plate comprising a hardened plastic composition including reenforcing fibres as its major constituent, said fibres being bonded into an integrated mass by a hardened rubber-like material.

8. In a refrigerator car a doorway and door therefor, a threshold plate secured in said doorway to underlie said door when closed, saidplate comprising a hardened plastic composition including asbestos bres as its major constituent, said fibres being bonded into an integrated mass by a hardened rubber material.

WALTER J. HEN'NESSY. 

